Why is the date 12/31/1969 next to apps in app manager on mt Lg phone

[ssmarie53]

I was going through all the apps on my android LG tribute 5 and next to as lot of the apps is the date 12/31/1969. I've never seen a date like that on any of my other android phoned. Why is that old old date next o the apps. (Yes I'm new to this)